During the last fifty years, missile and target speeds have increased to a great extent, requiring detection and guidance systems associated with automated target recognition systems to be pushed forward. This can result in larger time delays and larger detection errors due to incomplete or inaccurate encounter information. Accordingly, it has been necessary to increase warhead beamwidths to fill the larger volumes of uncertainty with a consequent reduction in effectiveness. Optical fuzing sensors have been proposed to overcome these deficiencies. Unfortunately, these optical sensors require complex and difficult alignments, leading to significant expense, and are vulnerable to error due to misalignment of the optical components comprising the sensor.
FIG. 1 illustrates a prior art fuzing sensor 10. The illustrated sensor 10 can be mounted on a moving object, such as a missile, and utilized to detect objects in or around a path of motion associated with the moving object. The fuzing sensor 10 includes a plurality of transmitters (not shown) in an outer ring 12 of the sensor. Each transmitter projects respective first and second beams of light forward of the sensor. In the illustrated sensor, the transmitters are aligned such that the first set of light beams provided from the plurality of transmitters are projected at a common first angle to a surface of the outer ring 12, such that when the fuzing sensor 10 is rotated about a central axis, the first set of light beams combine to trace a first cone 14 in the space forward of the sensor. Similarly, the second set of light beams provided from the plurality of transmitters are projected at a common second angle to a surface of the outer ring 12, such that when the fuzing sensor 10 is rotated, the second set of light beams combine to trace a second cone 16 in the space forward of the sensor.
When an object intersects one or both of the cones 14 and 16, light from the light beams is reflected back toward the sensor. This light can be detected at a central receiver 22 to determine the presence of objects within the scanning range of the sensor. The central receiver 22 contains a plurality of detectors (not shown) in a focal plane 24 at the rear of the sensor 10. Each detector is aligned to view a region in space along the cones 14 and 16 defined by the transmitters. This is facilitated by a common receiver optic 26 containing one or more lenses to collect reflected light and direct it to the focal plane 24 for detection at the detectors.
It will be appreciated that precise alignment of all elements of the sensor module 10 is necessary to ensure proper detection of detected light at the focal plane. A typical module 10 can include sixteen transmitters, each producing two beams, one associated with each cone 14 and 16, and thirty-two detectors, each configured to detect reflecting light associated with one of the beams. Each of the transmitters and detectors must be co-aligned precisely along a common optical axis of the sensor module 10. If any of these forty-eight elements are faulty or misaligned, the entire module 10 must be reworked. Further, it will be appreciated that the individual transmitters must contain fairly complex optics to deflect a generated beam to a region easily detectable from the central receiver 22. Accordingly, the transmitters can be unnecessarily expensive and subject to internal misalignment.